KR20220163507A - The pellicle and pellicle assembly - Google Patents

Abstract

The present invention relates to a pellicle assembly comprising a pellicle frame defining a surface to which the pellicle is attached. The pellicle assembly includes one or more three-dimensional expandable structures that allow the pellicle to expand under stress. The present invention also relates to a pellicle assembly for a patterning device comprising one or more actuators that move the pellicle assembly toward and away from the patterning device.

Description

The pellicle and pellicle assembly

This application claims the priority of EP application 17176205.7, filed on June 15, 2017, and EP application 17190503.7, filed on September 12, 2017, which are incorporated herein by reference in their entirety.

The present invention relates to a pellicle and a pellicle assembly. The pellicle assembly may include a pellicle and a frame for supporting the pellicle. A pellicle may be suitable for use with a patterning device for a lithographic apparatus. The present invention has a specific, but not exclusive, use in the context of EUV lithography apparatus and EUV lithography tools.

A lithographic apparatus is a machine configured to apply a desired pattern on a substrate. A lithographic apparatus may be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus may, for example, project a pattern from a patterning device (eg a mask) onto a layer of radiation-sensitive material (resist) provided on a substrate.

The wavelength of radiation used to project a pattern onto a substrate by a lithographic apparatus determines the minimum size of features that can be formed on that substrate. A lithographic apparatus using EUV radiation, which is electromagnetic radiation having a wavelength in the range of 4 to 20 nm, has smaller features on the substrate than a conventional lithographic apparatus, which may use electromagnetic radiation having a wavelength of 193 nm, for example. can be used to form

A pattern may be imparted to the radiation beam in a lithographic apparatus using a patterning device. The patterning device may be protected from particle contamination by the pellicle. A pellicle may be supported by a pellicle frame.

The use of pellicles in lithography is well known and well established. A typical pellicle in a DUV lithography apparatus is a membrane that is positioned away from the patterning device and, in use, is out of the focal plane of the lithographic apparatus. Since the pellicle is out of the focal plane of the lithographic device, contaminant particles landing on the pellicle are out of focus in the lithographic device. As a result, images of contaminant particles are not projected onto the substrate. If no pellicle is present, contaminant particles landing on the patterning device will project onto the substrate and introduce defects into the projected pattern.

It may be desirable to use a pellicle in an EUV lithography apparatus. EUV lithography differs from DUV lithography in that it is typically performed in a vacuum and the patterning device is typically reflective rather than transmissive.

It would be desirable to provide a pellicle and/or pellicle assembly that overcomes or alleviates one or more problems associated with the prior art. Embodiments of the invention described herein may have use in an EUV lithography apparatus. Also, embodiments of the present invention may have use in a DUV lithography apparatus or another type of lithography apparatus.

According to a first aspect described herein, a pellicle assembly is provided. The pellicle assembly includes a pellicle frame defining a surface to which the pellicle is attached. The pellicle assembly also includes one or more three-dimensional expansion structures that allow the pellicle to expand under stress.

In this way, the life and reliability of the pellicle assembly can be increased.

At least one of the three-dimensional inflatable structures may be formed within the pellicle frame and imparted to the pellicle. Three-dimensional inflatable structures can also be imparted to the pellicle, for example, by forming the three-dimensional inflatable structures within the pellicle frame and placing the pellicle over the pellicle frame.

At least one of the three-dimensional inflatable structures may form a spring. For example, the spring may include at least one V-shape formation formed within the pellicle frame. At least one structure may include a plurality of springs formed within the pellicle frame and positioned around the center of the pellicle. The center of the pellicle is the part of the pellicle that is not in direct contact with the frame. In this way, the control of the stress in the pellicle can be more accurately controlled. At least one spring may be a leaf-spring.

At least one of the three-dimensional expandable structures may be present in the center of the pellicle.

The frame may include a substrate, and the pellicle assembly may include at least one spring layer between the substrate and the pellicle. At least one spring may be formed in the spring layer. Additionally, the addition of a spring layer increases the ability to select a desired stress within the pellicle.

At least one three-dimensional intumescent structure may include a herringbone pattern. The herringbone pattern may extend over the entire pellicle or in portions outside the pellicle (eg, non-image field).

At least one three-dimensional intumescent structure may induce roughness across the surface of the pellicle.

According to a second embodiment described herein, a pellicle assembly is provided that includes a pellicle frame defining a surface to which the pellicle is attached. The surface includes at least one adhesive border to reduce adhesive spreading. The provision of an adhesive border reduces the tendency of the adhesive to spread and thus reduces contamination of the space between the patterning device and the pellicle.

The at least one adhesive border may include a circular border. Additionally or alternatively, the at least one adhesive border may include a line border. By providing a circular border, adhesive can be applied within the circular border, allowing the adhesive to spread and center within the circular border while reducing the amount of adhesive that extends beyond the circular border. In this way, the precision with which the adhesive can be applied is advantageously increased.

The line boundary may be located adjacent to an edge of the pellicle frame, the edge of the frame adjacent to the center of the pellicle, and the center of the pellicle being the portion of the pellicle that does not directly contact the pellicle frame.

A line boundary may be located between the circular boundary and the center of the pellicle.

At least one boundary may include a groove in the frame.

The pellicle assembly may include an adhesive substantially concentric with the circular boundary.

According to a third embodiment described herein, a pellicle assembly is provided that includes a pellicle frame, a pellicle, and one or more actuators for moving the pellicle assembly towards and away from a patterning device. In this way, the space between the pellicle and the patterning device can be opened and closed to allow processing of that space. For example, when opened, the space may be flushed, while when closed, the space may be sealed and pressure controlled.

The actuators are configured to transition the pellicle assembly between a closed configuration in which a substantially sealed volume is formed between the pellicle and the patterning device, and an open configuration in which the volume between the pellicle and the patterning device is in fluid communication with the surrounding environment. can be configured.

According to a fourth aspect described herein, a pellicle assembly is provided that includes a pellicle frame defining a surface to which the pellicle is attached. The pellicle frame includes a first material having a first coefficient of thermal expansion (CTE) and a second material having a second coefficient of thermal expansion (CTE). In this way, the overall CTE of the pellicle frame can be adjusted and selected to reduce (or increase) the difference from the CTE of the pellicle. The difference in CTE between the pellicle and the pellicle frame induces stresses in the pellicle after processing (such as annealing) during manufacturing. By controlling the overall CTE of the pellicle frame, the amount of stress in the pellicle can be controlled.

The first material may include silicon. The first material may include a plurality of perforations and the second material is positioned within the plurality of perforations. In other embodiments, the first material can include one or more channels and the second material can be provided in one or more channels.

The second material can at least partially surround the first material.

The second material may include metal. For example, the second material may include aluminum and/or molybdenum.

According to a fifth aspect described herein, a pellicle assembly is provided that includes a pellicle frame defining a surface to which the pellicle is attached, and the pellicle frame is bonded to the pellicle. The pellicle may be an annealed pellicle, and the frame may be bonded to the pellicle after such annealing.

The pellicle frame may include a material that has a lower coefficient of thermal expansion (CTE) than the CTE of silicon. For example, the pellicle frame may include a glass-ceramic material such as ZERODUR®.

The pellicle frame may be bonded to the pellicle using a bonding procedure that operates at temperatures less than approximately 160 °C. In this way, a pellicle frame comprising silicon can be used, while a non-operational stress (i.e., pre-stress) within the pellicle of approximately 200 MPa can be achieved. have.

The pellicle frame may be bonded to the pellicle using at least one of optical contact bonding, hydrogen bonding, gold diffusion bonding, or anodic bonding. It will be appreciated that any other bonding method may be used, with a particular bonding method operating at a temperature that produces a desired pre-stress in the pellicle after fabrication. By way of example only, other examples of bonding include mechanical (e.g., bolts, fasteners, etc.), ceramic green body bonding (two pieces of ceramic material in a green state are bonded together, changes to a monolithic part during sintering, another common term being co-fire bonding], direct bonding, glass bonding, atomic diffusion bonding, and laser ablation assisted bonding. .

The pellicle frame may be formed in a single piece. That is, the pellicle frame may be made not to include a plurality of pieces connected to form a whole (eg, via adhesive or mechanical holding means). In this way, the number of interfaces between the components of the pellicle assembly is reduced, reducing particulate contamination.

The pellicle frame may include an inert coating to reduce outgassing.

The pellicle of any one of the preceding embodiments may include molybdenum disilicide (MoSi ₂ ). The stress in the pellicle may range from 100 MPa to 250 MPa at room temperature, for example approximately 200 MPa.

The pellicle may include a graphite-based material. The stress in the pellicle may range from 300 MPa to 450 MPa at room temperature, for example approximately 400 MPa.

According to a sixth aspect described herein, a lithographic apparatus is provided that is arranged to project a pattern from a patterning device onto a substrate. A pellicle according to any of the foregoing embodiments is positioned in the vicinity of the patterning device to prevent particles from contacting the patterning device.

According to a seventh aspect described herein, a method of manufacturing a pellicle assembly is provided. The method includes placing a pellicle on a substrate, bonding the pellicle frame to the pellicle such that the pellicle is between the pellicle frame and the substrate, and etching the substrate to leave the pellicle and the pellicle frame.

The pellicle frame may be bonded to the pellicle at temperatures less than 160 °C.

The method may further include annealing the pellicle after placing the pellicle on the substrate and before bonding the pellicle frame to the pellicle.

According to an eighth aspect described herein, a pellicle assembly is provided that includes a pellicle frame defining a surface to which the pellicle is attached, and a computer readable and writable tracking device is provided on or in the pellicle frame.

The tracking device may be configured to store a unique identifier of the pellicle and/or pellicle assembly.

The tracking device may be configured to store information specific to the pellicle, such as operational data representing the usage history of the pellicle and/or offline measured parameters (eg transmission, reflectivity, etc.).

According to a ninth aspect described herein, there is provided a lithographic apparatus arranged to project a pattern from a patterning device onto a substrate, wherein the transceiver arrangement is a tracking device of a pellicle assembly according to the eighth aspect. and a controller comprising a processor configured to execute computer readable instructions to read from and write to.

The computer readable instructions may be configured to cause a processor to obtain one or more operational data items from the tracking device and determine whether the one or more operational data items exceed a threshold.

The computer readable instructions may be configured to cause the processor to cause the lithographic apparatus to unload the pellicle assembly in response to determining that the one or more operational data items exceed a threshold.

The computer readable instructions may be configured to cause the processor to cause the transceiver component to write data to the tracking device indicating that the pellicle assembly has been unloaded.

The computer readable instructions may be configured to cause the processor, in response to determining that the one or more operational data items do not exceed a threshold, to cause the transceiver to write operational data to the tracking device during use of the lithographic apparatus.

According to a tenth aspect described herein, a pellicle assembly is provided, the pellicle assembly includes a pellicle frame defining a surface to which the pellicle is attached, wherein the pellicle is configured to exhibit one or more wrinkles when in use, and wherein the pellicle assembly includes one or more wrinkles. The corrugations are configured to reflect a portion of the incident radiation beam away from the substrate.

The pellicle can be configured such that the wrinkles create a maximum angle greater than 35 mrad with respect to the plane defined by the surface of the patterning device.

The pellicle can be configured such that the wrinkles create a maximum angle less than 300 mrad with respect to the plane defined by the surface of the patterning device.

The pellicle may be configured to reflect approximately 0.4% of an incident radiation beam during use.

According to an eleventh embodiment described herein, a pellicle frame defining a surface to which a pellicle is attached, and at least one tensile layer provided on the surface of the pellicle and extending inward beyond an inner edge of the pellicle frame. There is provided a pellicle assembly comprising a. The at least one tensile layer serves to strengthen the pellicle assembly and maintain tension in the pellicle.

At least one of the one or more tensile layers may be provided on a top surface of the pellicle such that the pellicle is positioned between the tensile layer and the frame. At least one of the one or more tensile layers may be provided on the lower surface of the pellicle. The one or more tensile layers may include a first tensile layer provided on the upper surface of the pellicle and a second tensile layer provided on the lower surface of the pellicle.

At least one of the one or more tensile layers includes a first portion extending inwardly from an inner edge of the pellicle frame and a second portion extending outwardly from the inner edge of the pellicle frame, the second portion being longer than the first portion. In this way, most of the tensile layer can be in communication with the pellicle frame (either directly or via the pellicle), further strengthening the pellicle assembly.

At least one of the one or more tensile layers may comprise a multilayer structure.

According to a twelfth embodiment described herein, there is provided a lithographic apparatus arranged to project a pattern from a patterning device onto a substrate, comprising a pellicle assembly according to the eleventh embodiment.

According to a thirteenth embodiment described herein, a dynamic gas lock for a lithographic apparatus comprising a pellicle assembly according to any of the previously described pellicle assemblies is provided.

It will be appreciated that features described in connection with one or more of the above-described embodiments may be used in combination with other embodiments.

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings:
1 schematically illustrates a lithography system comprising a lithographic apparatus comprising a pellicle assembly;
2 schematically shows a pellicle assembly;
Figure 3 schematically illustrates the construction steps of a pellicle assembly having expandable structures that allow the pellicle to expand under stress;
Fig. 4 schematically shows the pellicle of Fig. 3 in plan view;
5 is a graph showing how the stress in the pellicle varies with the stiffness of the inflatable structures shown in FIG. 3;
Figure 6 schematically illustrates the construction steps of a pellicle assembly with different inflatable structures;
7 schematically illustrates a pellicle assembly having a plurality of inflatable structures;
8 shows a substrate etched to provide inflated structures that act in two dimensions;
9 shows a substrate provided with herringbone expansion structures;
10 schematically shows a pellicle assembly having herringbone inflating structures along an edge portion of the pellicle assembly;
11 schematically illustrates a pellicle assembly having herringbone inflated structures across the surface of the pellicle;
Fig. 12 schematically shows a pellicle with herringbone inflatable structures;
13 schematically illustrates mechanical bending of a pellicle assembly to reduce tension in the pellicle;
14 schematically illustrates mechanical bending of a pellicle assembly to increase tension in the pellicle;
Fig. 15 schematically shows the configuration of a pellicle having expanded structures provided by surface roughness;
Figure 16 schematically illustrates an alternative configuration of a pellicle with inflated structures provided by surface roughness;
17 schematically shows a pellicle frame including an adhesive boundary;
18 shows a pellicle frame including an adhesive border;
19A shows the pellicle assembly in an open configuration;
19B shows the pellicle assembly in a closed configuration;
19C shows the pellicle assembly of FIG. 19B after flushing the peripheral volume;
20A to 20C schematically illustrate steps for manufacturing a pellicle frame according to an embodiment;
21A and 21B schematically depict alternative examples of a pellicle frame;
22 schematically illustrates a pellicle assembly having a pellicle frame according to one embodiment;
23A and 23B schematically illustrate steps for manufacturing a pellicle assembly according to another embodiment;
24 is a graph showing how the pre-stress in the pellicle varies with bonding temperature in the method shown in FIG. 23;
25 schematically illustrates the reflection of radiation from a pellicle towards a substrate;
26 schematically illustrates the reflection of radiation away from the substrate from a corrugated pellicle; and
27A-27C schematically illustrate exemplary configurations of a pellicle assembly reinforced by application of at least one tensile layer.

1 shows a lithography system that includes a pellicle assembly 15 according to one embodiment described herein. The lithography system includes a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to produce a beam of extreme ultraviolet (EUV) radiation B. A lithographic apparatus (LA) comprises an illumination system (IL), a support structure (MT) configured to support a patterning device (e.g. a mask), a projection system (PS) and a substrate (W) configured to be supported. and a substrate table (WT). The illumination system IL is configured to condition the radiation beam B before the beam is incident on the patterning device MA. The projection system is configured to project the radiation beam B (now patterned by the mask MA) onto the substrate W. The substrate W may include previously formed patterns. In this case, the lithographic apparatus aligns the patterned beam of radiation B with a pattern previously formed on the substrate W.

Radiation source SO, illumination system IL, and projection system PS may all be constructed and arranged to be isolated from the external environment. A gas (eg hydrogen) at a pressure below atmospheric pressure may be provided to the radiation source SO. A vacuum may be provided to the illumination system IL and/or the projection system PS. A small amount of gas (eg hydrogen) at a pressure well below atmospheric pressure may be provided to illumination system IL and/or projection system PS.

The radiation source SO may take any form, for example a type that may be referred to as a laser generated plasma (LPP) source. In an alternative example, the radiation source SO may include one or more free electron lasers. One or more free electron lasers may be configured to emit EUV radiation, which may be provided to one or more lithographic devices.

A radiation beam B passes from a radiation source SO to an illumination system IL configured to condition the radiation beam. The illumination system IL may include a facetted field mirror device 10 and a facetted pupil mirror device 11 . The faceted field mirror device 10 and the faceted pupil mirror device 11 together provide the radiation beam B with a desired cross-sectional shape and a desired angular distribution. The radiation beam B passes from the illumination system IL and is incident on the patterning device MA held by the support structure MT. The patterning device MA is protected by a pellicle 19 held in place by a pellicle frame 17 . The pellicle 19 and the pellicle frame 17 together form the pellicle assembly 15 . A patterning device MA (which may for example be a mask) reflects and patterns the radiation beam B. The illumination system IL may include other mirrors or devices instead of, or in addition to, the facet field mirror device 10 and the facet pupil mirror device 11 .

After reflection from the patterning device MA, the patterned radiation beam B enters the projection system PS. The projection system includes a plurality of mirrors, which are configured to project the radiation beam B onto a substrate W held by a substrate table WT. Projection system PS may apply a reduction factor to the radiation beam to form an image having features that are smaller than corresponding features on patterning device MA. For example, a reduction factor of 4 may be applied. A patterned beam of radiation incident on the substrate W may include a band of radiation. The band of radiation may be referred to as an exposure slit. During scanning exposure, movement of the substrate table WT and support structure MT may be made such that the exposure slit advances across the exposure field of the substrate W. Although projection system PS has two mirrors in FIG. 1 , the projection system may include any number of mirrors (eg 6 mirrors).

The radiation source SO shown in FIG. 1 may include components not illustrated. For example, a spectral filter may be provided in the radiation source. The spectral filter may be substantially transmissive to EUV radiation, but substantially blocking radiation of other wavelengths, such as infrared radiation.

As briefly described above, the pellicle assembly 15 includes a pellicle 19 provided adjacent to the patterning device MA. A pellicle 19 is provided in the path of the radiation beam B, so that when the radiation beam B approaches the patterning device MA from the illumination system IL and by the patterning device MA, the projection system PS All pass through the pellicle 19 when reflected toward the . Pellicle 19 comprises a thin film that is substantially transparent to EUV radiation (although it will absorb a small amount of EUV radiation). The pellicle 19 serves to protect the patterning device MA from particle contamination. In this specification, the pellicle 19 may be referred to as an EUV transparent pellicle.

Although efforts may be made to maintain a clean environment inside the lithographic apparatus LA, particles may still be present inside the lithographic apparatus LA. In the absence of pellicle 19, particles may be deposited on patterning device MA. Particles on the patterning device MA may adversely affect the pattern imparted to the radiation beam B and thus transferred to the substrate W. The pellicle 19 provides a barrier between the environment of the patterning device MA and the lithographic apparatus LA to prevent the deposition of particles on the patterning device MA.

In use, the pellicle 19 is positioned away from the patterning device MA, which is sufficient so that any particles incident on the surface of the pellicle 19 are not in the focal plane of the radiation beam B. This separation between the pellicle 19 and the patterning device MA serves to reduce the extent to which any particles on the surface of the pellicle 19 impart a pattern to the radiation beam B. If a particle is present in the radiation beam B, but at a location that is not in the focal plane of the radiation beam B (i.e., the surface of the patterning device MA), then any image of the particle is focal at the surface of the substrate W. You will understand that this will not fit. In some embodiments, the spacing between the pellicle 19 and the patterning device MA may be, for example, between 2 mm and 3 mm (eg, about 2.5 mm). In some embodiments, as described in more detail below, the spacing between the pellicle 19 and the patterning device may be adjustable.

Figure 2 shows a schematic view of the pellicle assembly 15 and the patterning device MA in cross section and in more detail. The patterning device MA has a patterned surface 24 . A pellicle frame 17 supports the pellicle 19 around a perimeter portion of the pellicle 19 . The pellicle frame 17 has an attachment mechanism configured to make the pellicle frame detachably attachable to the patterning device MA (i.e., to make the pellicle frame attachable to and detachable from the patterning device MA) ( 22) may be included. Attachment mechanism 22 is configured to engage an attachment feature (not shown) provided on patterning device MA. The attachment feature may be, for example, a protrusion extending from the patterning device MA. Attachment mechanism 22 may include, for example, a locking member that engages the protrusion and secures pellicle frame 17 to patterning device MA. Note that although referred to herein as a pellicle frame, the pellicle frame 17 may be referred to as a pellicle border elsewhere. Additionally, the pellicle frame 17 (or “border”) may be attached to the mask through another pellicle frame. For example, referring to FIG. 4B of patent application WO 2016079051 A2, the pellicle membrane 19 attached to the patterning device MA through an attachment mechanism as shown in FIGS. 12 and 31 of WO 2016079051, the border portion 20 ) [in some configurations, this may correspond to a general, but not specific, element in the location of “frame 17” in this application] and a configuration is shown that includes an additional frame 17 . A plurality of attachment mechanisms and associated attachment features may be provided. Attachment mechanisms may be distributed around the pellicle frame 17 (eg two on one side of the frame and two on the opposite side of the frame). Associated attachment features may be distributed around the periphery of the patterning device MA.

A contaminant particle 26 is schematically shown in FIG. 2 . Contamination particles 26 are incident on the pellicle 19 and are retained by the pellicle 19 . The pellicle 19 keeps the contaminant particle far enough away from the patterned surface 24 of the mask MA so that it is not imaged onto the substrates by the lithographic apparatus LA.

A pellicle assembly according to one embodiment of the present invention allows a mask pattern (on the patterning device) to be provided that remains substantially defect-free during use (the mask pattern is protected from contamination by the pellicle).

The pellicle assembly 15 may be constructed by depositing a pellicle 19 (which may be made of, for example, polysilicon (pSi)) directly on top of a substrate that will provide the frame 17 . The substrate may be, for example, a silicon wafer. After deposition of the film of the pellicle 19, the substrate is selectively back-etched to form a frame 17 supporting the pellicle 19, removing the central portion of the substrate and leaving only the outer perimeter. can The pellicle 19 may have a thickness of about 15 to 50 nm, for example.

The pellicle 19 requires some level of "pre-stress" (i.e., a level of stress that is present within the pellicle 19 when not in use and thus not subject to radiation and gas pressure during scanning operations). The pre-stress in the pellicle 19 allows the pellicle 19 to withstand pressure differentials caused by changes in temperature and gas pressure during a scanning operation. However, if the pre-stress is too great, it will reduce the overall life of the pellicle assembly 15. As such, it is desirable to provide a minimum pre-stress (in the x-y plane shown) to the pellicle 19 to limit deflection (in the y direction) at a given pressure to the pellicle 19. When the deflection of the pellicle 19 is too great in the y direction, the pellicle 19 may break and/or contact other components in the peripheral area of the pellicle 19 .

Since the pre-stress of the pellicle 19 is preferably significantly lower than the highest tensile stress or yield strength of the material from which the pellicle 19 is formed, the pre-stress of the pellicle 19 is preferably limited. The margin between pre-stress and peak tensile stress should be as large as possible to increase the life and reliability of the pellicle 19 .

The pre-stress is applied to the pellicle 19 during deposition of the pellicle 19 on the wafer 17 through one or more mechanisms including stoichiometry, hydrogenation, control of crystallite size, doping, and selective mismatching of coefficients of thermal expansion (CTE). ) can be incorporated into Additionally, pellicle 19 may include multiple layers (eg, capping layers to protect pellicle 19 from hydrogen radicals). Due to the CTE mismatch between the layers of portions of the pellicle 19 of the pellicle assembly 15 and the process of heteroepitaxy in which different layers of the pellicle 19 can be deposited, each layer of the multi-layer pellicle 19 The stresses in can be different.

The use of stoichiometry, hydrogenation, choice of grain size (i.e., number of grain boundaries), doping, etc. can all affect the chemical stability of the layers of pellicle 19. In general, the process used to fabricate pellicle 19 can induce a desired pre-stress, where the desired pre-stress is relatively high; It may not have the most stable configuration from the point of view. For example, a pellicle constructed from molybdenum disilicide (MoSi ₂ ) oxidizes exponentially faster as a function of pre-stress. Moreover, it is generally difficult to obtain pre-stress values below 600 MPa in a complementary metal-oxide-semiconductor (CMOS) based fabrication process using the previously described methods. In some embodiments, it is desirable to obtain a pellicle 19 having a pre-stress on the order of approximately 100 to 200 MPa.

Additionally, the pellicle frame 17 is generally less flexible than the pellicle 19, inducing internal stresses in addition to the desired pre-stress. As such, for example, a pre-stress of 100 MPa in the pellicle 19 may actually be a pre-stress of 100 MPa ± the deviation caused by the pellicle frame 15 . In other words, some parts of the pellicle 19 may be under higher stress than others, leading to greater points of mechanical weakness in the pellicle 19 .

The average pre-stress in pellicle 19 is generally equal in both the x and y dimensions shown. In one embodiment, it is desirable to avoid wrinkles at high angles (on the order of 300 mrad) (between the xy plane and the z-dimension). One way to reduce local wrinkles with high angles is to reduce the pre-stress in the scanning (x) direction. The stress in the scanning (x) direction only needs to be slightly larger than the Poisson's ratio (ν) multiplied by the stress (σ _y ) in the y-direction (approximately 0.17 to 0.25 for MoSi ₂ ) to avoid buckling during relaxation - In other words:

σ _x = ν*σ _y

During exposure, the stress (σ _y ) in the non-scanning (y) direction will decrease approximately ten times faster than the stress (σ _x ) in the scanning (x) direction. However, since σ _x will be much lower than ν*σ _y , the buckle modes that can occur in the pellicle 19 within the exposure slit will be of lower order, hence the likelihood of local high crease angles. lower The lowest-order buckled mode is one cycle of the sine, i.e., a single crease. This takes energy to pull the pellicle 19 into a higher order buckled mode (ie, such that the pellicle 19 contains multiple pleats). The more energy present, the more likely it is that the pellicle 19 will (locally) be pulled at a high angle, eg due to imperfections in the pellicle 19 locally. As such, in embodiments, using the techniques described herein, the amount of pre-stress in the scanning direction may be reduced.

It is desirable to isolate the internal microstructure of pellicle 19 from the pre-stress within pellicle 19 . That is, it is advantageous to control the pre-stress within the pellicle 19 mechanically (or non-intrinsically), rather than through the intrinsic microstructure of the pellicle 19 . This allows the pre-stress within the pellicle 19 to be adjusted to a desired level, while allowing the pellicle 19 to be made as chemically inert as possible.

3 schematically illustrates manufacturing steps of a pellicle assembly 35 according to one embodiment. The pellicle assembly 35 is fabricated by etching two notches 36 and 37 into a substrate 38 (e.g., a silicon wafer) that will provide a frame, as shown in FIG. 3A. A pellicle 19 is deposited on the notched substrate 38 as shown in FIG. 3B. The substrate 38 is then back-etched to provide a pellicle assembly 35 having a frame 39 as shown in FIG. 3C. After back-etching, the notches 36 and 37 result in a frame 39 comprising two inflation structures (eg v-shaped formations) 36', 37' in the form of leaf springs. . The leaf springs 36', 37' reduce the pre-stress of the pellicle 19 in the x-dimension (ie, the scanning direction).

The length and thickness of the leaf springs 36', 37' can be controlled by adjusting the depth of the notches 36, 37 (ie, their size in the z dimension) and position in the x-y plane of the substrate 38. can In this way, the reduction in stress provided by the leaf springs 36', 37' can be controlled. Also, the stiffness of the leaf springs can be adjusted independently in both the scanning (x) and non-scanning (y) dimensions. For example, as shown in FIG. 4 , notches may be positioned on the substrate to provide lower stress in the scanning direction (x) than in the non-scanning direction (y). In particular, in Fig. 4, notches 40 and 41 are positioned closer (in the x-dimension) to the desired image field 42, resulting in a relatively flexible leaf spring, while notches 43 and 44 are (y -dimension) may be positioned farther from the desired image field 42 to create stiffer leaf springs.

5 is a graph showing how the stress in a pellicle varies as a function of the stiffness of a leaf spring (such as leaf springs 36', 37'). It can be seen in FIG. 5 that by varying the stiffness of the leaf springs 36', 37', it is possible to control the pre-stress in the pellicle within a broad band.

Therefore, the use of one or more expandable structures can increase the margin between the pre-stress in a pellicle after production and the highest tensile stress of that pellicle, improving the life and reliability of the pellicle. Additionally, in case of catastrophic failure of the pellicle, the reduced tension achieved through the inflatable structure means that less elastic energy is stored within the pellicle. As such, it is less likely that fragments of the pellicle will be ejected to other areas of the lithographic apparatus due to breakage of the pellicle.

Although intumescent structures comprising a single notch are shown in FIGS. 3 and 4 , intumescent structures with additional notches and/or other patterns may be etched into the substrate upon which the pellicle frame is formed to provide intumescent structures of different properties. will understand In this way, pellicles with different pre-stresses can be provided. In some embodiments, additional layers may be used in the fabrication of the pellicle assemblies to provide more complex intumescent structures. For example, FIG. 6 schematically illustrates steps in the manufacture of pellicle assembly 55 ( FIG. 6D ). Pellicle assembly 55 is fabricated by etching serrations 51 and 52 into a substrate 53 (eg, a silicon wafer). A spring layer 54 is deposited on the substrate 53 so that the spring layer 54 is received within and takes the form of the serrations 51 and 52 . The spring layer 54 may be formed of, for example, a metal such as copper, gold, or silver. In other embodiments, spring layer 54 may be formed from other materials such as SiOx, SiN or MoSi. A shield layer 56 is deposited between the substrate 53 and the spring layer 54 over the desired image field. Shielding layer 56 need not be deposited within serrations 51 and 52 . Removal of shield layer 56 after depositing spring layer 54 results in the configuration illustrated in FIG. 6C, where spring layer 54 is generally confined to regions within serrations 51 and 52. . A pellicle layer 57 is deposited on the spring layer 54 and the substrate 53 . Back-etching of the substrate 53 provides a pellicle assembly 55 having two intumescent structures 58 and 59 . In addition to the properties of the serrations 51 and 52 (eg, depth, width), the properties of the spring layer 54 can be selected to obtain a desired pre-stress within the pellicle 57, and very A pellicle frame with a low stiffness level can be achieved. Although a single spring layer 54 is shown in the exemplary configuration of FIG. 6, it will be appreciated that in other embodiments more than one spring layer may be provided. If more than one spring layer is provided, spring layers of different materials may be provided.

In some embodiments, the substrate and/or spring layer(s) may be etched to isolate the inflation structures from each other. In a theoretically ideal configuration, the pellicle could be suspended from the pellicle frame by an infinite number of inflatable structures (eg springs), each inflatable structure having no internal connection with any other inflatable structures. It is not possible to provide an infinite number of inflated structures, but from the teachings herein, it is understood that different etching patterns can be used within the general techniques described above to isolate each inflated structure from each other inflated structure. will understand FIG. 7 schematically illustrates a plan view of a pellicle frame 75 , wherein the frame 70 has been etched to provide a plurality of isolated expansion structures in the form of springs 71 supporting a pellicle 72 .

Although the preceding examples have described inflatable structures operating in a single dimension expanding and contracting along the x-axis in FIGS. 3 and 6 , other embodiments may operate in multiple dimensions to control stress within the pellicle in both the x and z dimensions. Functional inflatable structures can be formed. 8 is a photograph showing a perspective view of a substrate that has been etched to provide expansion structures that function in both the x and z dimensions shown.

In one embodiment, the pellicle frame may be etched to provide what is referred to as a “herringbone” pattern comprising sawtooth (or zigzag) structures in the x-y plane, z-y plane and z-x plane. FIG. 9A is a diagram illustrating a membrane 80 having an outer limit shown schematically by dashed outline 81 . Referring to FIG. 9B, the membrane 80 has been folded to provide a herringbone structure 80'. In the herringbone structure 80', it can be seen that the membrane 80 is smaller than the outer limit 81.

The herringbone structure can be used in a number of ways within a pellicle assembly. In one embodiment, a herringbone structure is applied to the outer portion of the pellicle assembly. Referring to FIG. 10, the pellicle assembly 90 has an image field (or center) portion 92 and a pellicle 91 having an expandable structure in the form of a herringbone portion 93 on the frame (or edge) portion of the pellicle assembly 90. ). In Fig. 10, the herringbone structure is schematically illustrated with hatching. The edge portion 93 of the herringbone pattern may be constructed according to the techniques previously described with reference to FIG. 6 using, for example, a different etch pattern.

In another embodiment, the entire surface of the pellicle may be formed to include a herringbone structure. Referring to FIG. 11 , there is shown a pellicle assembly 100 in which the entire pellicle 101 including the image field portion 102 comprises a herringbone structure (schematically illustrated by hatching). By forming the entire pellicle 101 in a herringbone structure as in the exemplary configuration of FIG. 11 , the entire surface of the pellicle 101 contributes to the reduction of pre-stress across the pellicle 101 . In the test, a pellicle with a herringbone pattern was modeled using the finite element method, and the results showed that the average stress in the pellicle could be reduced by more than 10 times, while the maximum stress experienced by any part of the pellicle was higher than that of a pellicle without a herringbone structure. It was shown that it was reduced more than 6 times compared to

When the herringbone structure is applied over the entire surface of the pellicle (or at least most of the surface of the pellicle), the pellicle can be formed to have a total pre-stress of 0 Pa. In an exemplary embodiment, the out-of-plane structure (ie, the size of the inflated structure(s) in the z-dimension) is on the order of 0.1 mm to 0.5 mm, and the herringbone pattern has a spatial frequency of 0.2 mm to 1 mm. In this embodiment, the pellicle will not be pre-stressed after construction, since the additional surface area provided by the herringbone structure (relative to a flat pellicle) is more than an order of magnitude of shrinkage of the pellicle during production. Surprisingly, while a pellicle that is not pre-stressed will generally sag to an unacceptable degree during use (i.e., deflection that brings particles on the pellicle into the focal plane), herringbone structures are more resistant to pellicles than flat pellicles in at least one direction. It has been found to have an additional advantage in that it introduces significant bending stiffness. Referring to FIG. 12, a pellicle 120 having a herringbone structure is illustrated. The herringbone structure of pellicle 120 provides relatively high bending stiffness for bending about axis 121, reducing deflection of pellicle 120 having lower bending stiffness about axis 122. The bending stiffness introduced by the herringbone structure suppresses out-of-plane deviations (eg, deflection in the z-dimension) during use.

Therefore, the use of one or more intumescent structures comprising herringbone structures over the entire pellicle or on the outside of the pellicle (e.g., frame, edge or non-image field) can reduce the pre-stress in the pellicle after production and the peak tensile of the pellicle. It is possible to increase the margin between stresses, thereby improving the life and reliability of the pellicle. Additionally, in case of catastrophic failure of the pellicle, the reduced tension achieved through the herringbone structure means that less elastic energy is stored within the pellicle. As such, it is less likely that fragments of the pellicle will be ejected to other areas of the lithographic apparatus due to breakage of the pellicle.

A herringbone pattern can be formed in a pellicle using methods generally described above. That is, the herringbone pattern may be first etched into the substrate (eg, silicon wafer) prior to deposition of the pellicle on the substrate and prior to back-etching the substrate. Compared to the methods previously described with reference to FIGS. 3 and 6 , to provide a herringbone over the entire surface of the pellicle, the entire surface of the substrate, not just the outer portion of the substrate forming the pellicle frame, is pre-etched. It can be. In other embodiments, the stress within the pellicle can be adjusted by introducing localized portions of herringbone patterns only when the pellicle is expected to be subjected to a thermal load during use.

In one embodiment, stress within the pellicle may be controlled through mechanical bending of the substrate prior to depositing the pellicle material onto the substrate. For example, referring to FIG. 13A , the substrate 130 may be mechanically bent in an arc shape. A pellicle 131 may be deposited on the outer (convex) surface of the bent substrate 130 (FIG. 13B). Finally, the mechanical load within the substrate 130 can be released, introducing mechanical compression into the pellicle 131 (FIG. 13C). Due to the mechanical compression introduced into the pellicle 131, the tension in the pellicle 131 after further production steps (eg, back-etching, annealing, etc.) is reduced when the pellicle 131 is initially deposited on a flat substrate. will be lower than

Also, bending of the substrate prior to depositing the pellicle material on the substrate may be used to increase tension. For example, referring to FIG. 14A , the substrate 140 may be mechanically bent in an arc shape. A pellicle 141 may then be deposited on the inner (concave) surface of the bent substrate 140 (FIG. 14B). Finally, the mechanical load within the substrate 140 may be released, introducing mechanical tension.

The mechanically added or removed stress from a pellicle as a function of the radius of curvature of the substrate on which the pellicle is deposited during fabrication may in some embodiments be calculated analogous to "Stoney's equation":

where E _s is the Young's modulus of the substrate, h _s is the thickness of the substrate, h _f is the thickness of the pellicle, ν _s is the Poisson's ratio of the substrate, and R is the radius of curvature of the substrate mechanically introduced through bending . However, it will be appreciated that the amount of stress added or removed may be different and may be less.

It should be understood that stress control within the pellicle through mechanical bending is not limited to a single layer and can be replicated with any additional layer of the pellicle deposited on the substrate. In this way, the stress of the individual layers of the pellicle can be tuned as desired. Also, the use of mechanical bending can be used to control stress in more than one direction. For example, the substrate can be mechanically bent in different directions. The bending direction may be different for different layers of the pellicle.

Additionally, a feedback loop may be provided in which a sensor (not shown) is provided to measure the forces occurring during deposition of the pellicle as the pellicle layer grows thicker. Mechanical bending of the substrate can then be controlled based on the feedback to ensure equal stress across the entire thickness of the pellicle layer. Feedback can be particularly advantageous in the first atomic layers of a pellicle as stress develops differently in the first atomic layers than in the 'bulk' of the pellicle.

It has been described above with reference to FIGS. 11 and 12 that a herringbone pattern can be created over the entire surface of the pellicle. In an alternative embodiment, other patterns or random "roughness" may be introduced into the pellicle during manufacture to lower the final pre-stress of the pellicle. Similar to the previously described methods, roughness may be introduced to the surface of the substrate on which the pellicle is to be deposited to introduce "roughness" to the pellicle. A number of mechanisms can be used to introduce roughness to the surface of a substrate. For example, referring to FIG. 15 , a low temperature plasma chemical vapor deposition (PECVD) oxide layer 152 (eg, silicon dioxide) may be provided on the surface of the silicon substrate 150 . The PECVD oxide layer 152 provides the backside “etch-stop” layer upon which the pellicle 151 is deposited. Low-temperature PECVD oxides have an inherent roughness much greater than that of silicon. Pellicle 151 will take on this roughness when deposited on PECVD oxide layer 152.

In other embodiments, potassium hydroxide (KOH) may be used to etch the surface of the silicon substrate on which the pellicle is to be deposited. In particular, resist is first deposited on a silicon substrate, and the deposited resist may be patterned into a pattern using lithography. For example, a checkerboard pattern can be formed in the resist. After forming a pattern in the resist with lithography, the silicon may be etched (eg, using KOH). For example, silicon can be etched to create inverted pyramid shapes, which provide the desired roughness. Thereafter, the resist may be removed and the substrate may be cleaned. The cleaned substrate may be oxidized with a thermal oxide to create an "etch stop" and round off any sharp edges created during etching. The pellicle can then be deposited onto the oxidized substrate ready for normal pellicle fabrication.

It will be appreciated that other etchants may be used. For example, in other embodiments, an isotropic dry or wet etch may be used. In another embodiment, the roughness may be created through an isotropic etch of the silicon dioxide prior to the removal of the resist.

The addition of "roughness" to the pellicle may be limited to portions of the pellicle rather than being provided over the entire surface of the pellicle. For example, roughness may be added to the pellicle along one or more edge portions of the pellicle, or at other portions of the pellicle, similar to the way the spring is created in the embodiment described with reference to FIGS. 3 and 6 . . For example, stress within a pellicle can be adjusted by introducing localized portions of roughness only when the pellicle is expected to be subjected to a thermal load during use.

The roughness of the pellicle or the lateral dimension of the features created by the addition of patterns is preferably greater than the thickness of the pellicle. For example, referring to FIG. 16 , the lateral dimension X of the features (shown forming a triangular pattern in the exemplary configuration of FIG. 16 ) is greater than the thickness y of the pellicle layer 161 .

In some embodiments, the dimensions and configuration of the roughness added to the pellicle may be selected to provide approximately 0.045 to 0.095% additional surface area across the pellicle over that provided by a flat pellicle. Once the pellicle is freestanding (eg, after other manufacturing steps of the pellicle assembly, such as back-etching), the stress relative to that provided by a flat pellicle is of additional surface area translated through the Young's modulus of the pellicle material. will be reduced by the function.

The pellicle may be attached to the pellicle frame using an adhesive. Manually dispensing the small amount of adhesive needed to attach the pellicle to the pellicle frame can be difficult due to process variations and operator inaccuracies. Problems can arise, for example, if too much adhesive is applied (process variations) and parts of the adhesive are positioned too far into the inside of the frame. Capillary effects between the frame and the pellicle may cause the adhesive to migrate inside the enclosed volume between the pellicle and the patterning device MA. Adhesive inside the enclosed volume can lead to severe contamination of the patterning device.

17 schematically shows a pellicle frame 171 . The pellicle frame includes a frame border with an inner edge 174. Beyond the inner edge 174, the center of the pellicle is not in direct contact with the frame. A circular border 172 is provided on the frame border. A circular border 172 has been carved into the material of the frame (which may be silicone, for example). By providing circles carved into the frame border, it has been found that the circles provide a centering function for the adhesive supplied to the central area of the circus. A droplet of adhesive with a high contact angle starts wetting immediately after application. Circular border 172 acts as a barrier allowing the adhesive to self-center within border 172 .

Also, an additional boundary 173 is provided. In the illustrated embodiment, the additional boundary 173 takes the form of a straight line etched into the frame 171 . Additional border 173 acts as an additional barrier in case too much adhesive is applied. 18A is a photograph illustrating the centering effect of circular border 172, where it can be seen that adhesive 180 formed a generally centered circular dot of adhesive generally concentric with circular border 172. In the illustrated embodiment, the diameter of circular boundary 172 is on the order of 1.4 mm.

Circular border 172 and additional border 173 may be provided by etching the substrate. For example, borders 172 and 173 may be laser etched into a silicon substrate.

FIG. 18B is a photograph showing the situation at the dot of adhesive 181 having too much volume added to the pellicle frame 171. In FIG. 18B, the additional boundary 173 acts as an additional barrier so that the adhesive 181 does not spread beyond the inner border 174 of the frame - which may contaminate the enclosed volume between the pellicle and the patterning device MA. It can be seen that there is - to prevent.

The provision of circular borders 172 and/or additional borders 173 significantly reduces the risk of adhesive reaching the enclosed volume and improves the ease and accuracy of application of adhesive that may be performed manually.

It will be appreciated that the pellicle frame to which the pellicle is attached is relatively rigid compared to the pellicle itself. As previously discussed, the stiffness of the frame in combination with the pre-stress added to the pellicle can cause the pellicle to wrinkle when the temperature rises during the scanning operation. During scanning, the temperature can rise to hundreds of degrees Celsius.

In one embodiment, a mechanism is provided to translate the pellicle frame in directions toward and away from the patterning device MA to close and open a region between the pellicle and the patterning device MA. Referring to FIG. 19 , a pellicle assembly 190 is shown with a patterning device MA. The pellicle assembly 190 includes a pellicle frame 191 and a pellicle 192 . Actuators (not shown) are provided to translate the pellicle assembly along the shown z-dimension. In FIG. 19A , the pellicle assembly is shown in an open configuration, where pellicle assembly 190 is spaced apart from patterning device MA. In the open configuration, the pressure in the volume between the pellicle 192 and the patterning device MA is equal, denoted P ₁ in FIG. 19A .

It will be appreciated that the actuators may take any suitable form, as will be apparent to one skilled in the art.

The actuators are configured to cause the pellicle assembly 190 to transition to a closed configuration by translating the pellicle assembly 190 toward the patterning device MA until the pellicle frame 191 physically contacts the patterning device MA. do. In a closed configuration, the volume between patterning device MA and pellicle 192 is physically isolated from the external environment surrounding patterning device MA. The pellicle frame 191 may include sealing members (not shown) on a surface 193 disposed to contact the patterning device MA. The patterning device MA may include corresponding sealing members (not shown) for interfacing with the pellicle frame 191 .

In FIG. 19B , the pressure in the enclosed space between the pellicle 192 and the patterning device MA is still the same pressure P ₁ as the pressure around the patterning device MA.

During the scanning operation, the pellicle assembly 190 may transition to a closed configuration, and gases may be flushed from the patterning device MA and the environment surrounding the pellicle assembly 190, thereby surrounding the patterning device MA. decreases the pressure in the environment. As shown in FIG. 19C, after flushing the surrounding area, the pressure in the volume between the patterning device MA and the pellicle 192 is greater than the pressure surrounding the patterning device MA (denoted P ₂ in FIG. 19C). Bigger. As such, the pellicle 192 may bend from the patterning device MA in the z-dimension.

Prior to transitioning the pellicle assembly 190 from an open configuration to a closed configuration, the ambient pressure surrounding the patterning device MA (indicated as P ₁ in FIG. 19A ) may optionally be adjusted. For example, in some embodiments, the pressure may be approximately 2 Pa through the introduction of a gas, such as hydrogen gas.

The thermal connection to the patterning device is improved by increasing the pressure between the patterning device MA and the pellicle 192 . This allows for greater cooling through conduction through the gas in the volume between the patterning device MA and the pellicle 192 . Also, pressure may be increased from the other side of the pellicle 192 to reduce the pressure differential across the pellicle 192 . In this way, the pressure difference across the pellicle 192 controls the tension within the pellicle 192 .

By ensuring that the tension of the pellicle 192 induced by the difference between the pressures (P ₁ , P ₂ ) is greater than the tension of the pellicle 192 induced by the frame 191, the pellicle 192 has a high It will wrinkle considerably less when subjected to heat load. Additionally, by closing the volume between the pellicle 192 and the patterning device MA, no continuation can enter that volume during the scanning operation.

In the previously described embodiments, it is shown that the substrate on which the pellicle is deposited may be a crystalline silicon wafer. The bias in the art to use crystalline silicon as a substrate for pellicles has many reasons, including that the industry has extensive experience in processing crystalline silicon wafers. Additionally, the coefficient of thermal expansion (CTE) of the crystalline silicon wafer (2.6 um/m/K) matches that of the polycrystalline pellicle material (about 4 um/m/K), allowing relatively little thermal stress to be introduced during the fabrication process. . Therefore, crystalline silicon has quickly become the default surface on which pellicles are grown, even when the pellicle is composed of a material with a different CTE than a polycrystalline pellicle material.

In some embodiments, the pellicle can be constructed from MoSi ₂ with a CTE of about 8 um/m/K or graphite-based materials with a CTE of about 1 um/m/K. As previously described, during annealing at high temperature (eg, approximately 800° C.) to improve the microstructure of the pellicle, the internal stress within the pellicle assembly is small (eg, close to zero). However, during cooling (eg to room temperature), a large CTE mismatch is introduced between the pellicle and the substrate, leading to a build-up of stresses and contributing to large pre-stresses in the pellicle assembly as described above.

In one embodiment, the CTE of the pellicle frame is tuned by creating the pellicle frame formed from a composite material. Referring to Figure 20a, a silicon wafer 200 to form a pellicle frame of the pellicle assembly is shown. It will be appreciated that in other embodiments the substrate may be of a different material.

A border region 201 defining the edges of the pellicle frame is defined on the substrate 200 . Although the border region 201 is shown in FIG. 20A as having a generally rectangular shape, it should be understood that other shapes may be used. For example, a circular pellicle frame may introduce fewer stress concentrations within the pellicle, and thus may be particularly advantageous in some embodiments. From within the border region 201 of the substrate 200, portions of silicon are removed to form a region 202 that includes one or more regions for receiving another material. The removed regions are filled with a second (or filler) material having a different CTE than silicon to form composite region 203 . After that, the configuration of the pellicle assembly using the substrate 200 may proceed normally. Composite zone 203 ensures that the pellicle frame of a pellicle assembly constructed using substrate 200 will have a desired CTE. The CTE can be adjusted by selecting the filler material and how the filler material is distributed within the border region 201 .

For example, in one embodiment, silicone may be removed from border region 201 in continuous band 210 as shown in FIG. 21A. In an alternative embodiment, the border region 201 may be perforated to define a plurality of perforations 215 . A filler material may then be applied to fill the perforations. It will be appreciated that the configurations shown in FIGS. 21A and 21B are exemplary only, and that material may be removed from border region 201 in any configuration.

In one embodiment, after filling, the filler material may partially or completely surround the border area. 22 shows a cross-sectional view of a pellicle assembly 223 surrounding a silicon substrate 221 with filler material 220 present in and around perforations in the silicon substrate 221 . Silicon substrate 221 and filler material 220 together form a pellicle frame 222 . In FIG. 22 , the substrate has been back-etched to form a pellicle assembly 223 with a pellicle 224 .

By using a filler material, the CTE of the pellicle frame can be reduced or increased to increase or decrease pre-stress in the pellicle.

The filler material can be any suitable material that has a different CTE than the substrate material (in one example, silicon) on which the pellicle frame will be formed and on which the pellicle will be deposited. By way of example only, the filler material can be a material with a relatively high CTE. Preferably, the filler material is a soft material. Preferably, the filler material is a non-outgassing material. In an exemplary embodiment, the filler material is metal. In certain instances, the filler material is aluminum or molybdenum, for example. In one embodiment, different amounts of substrate may be removed in different portions of the border portion. In this way, additional localized control over the pre-stress within the pellicle assembly can be achieved.

As previously discussed, once the filler material is added to the substrate, the use of the composite frame can be easily incorporated into existing manufacturing processes, since all other processing steps for manufacturing the pellicle assembly may advantageously not change. In one embodiment, rather than using a substrate to form the pellicle frame, the pellicle frame may be bonded to the pellicle in a separate operation. The substrate may then be completely etched (so that no part of the substrate remains within the pellicle assembly). The construction steps of an exemplary pellicle assembly 230 in which a pellicle 231 is deposited on a substrate 232 are shown in FIG. 23 . The substrate may be, for example, crystalline silicon. Once the pellicle 231 is deposited on the substrate 232, the pellicle may be annealed according to conventional pellicle manufacturing methods. However, after annealing, frame 234 may be bonded to pellicle 231 . The frame 234 is bonded to the opposite side of the pellicle on the side in contact with the substrate 232 . The substrate may then be fully back-etched to remove the substrate, leaving a pellicle assembly 230 comprising a pellicle 231 and a frame 234. In this way, the pre-stress in the pellicle after fabrication depends on the difference in CTE between the pellicle 231 and the frame 234 and the temperature at which bonding of the frame 234 to the pellicle 231 occurs.

It will be appreciated that the term "bonded" as used herein is used to distinguish the process by which a pellicle is deposited on a substrate. That is, in the previous configurations, the pellicle is deposited on the substrate and then attached to the substrate, while this differs from the current configuration in which the frame is bonded to the pellicle after the pellicle is annealed.

Frame 234 can be constructed from any material such that the CTE of frame 234 can be selected according to the desired properties of the pellicle assembly, such as pre-stressing. Additionally, the method of bonding the frame 234 (and thus the temperature) may be selected to obtain more desired properties of the pellicle assembly 230. For example, in one embodiment, the pellicle frame 234 may include a lithium-aluminosilicate glass-ceramic such as ZERODUR® from Schott AG. ZERODUR has a very low CTE, so there is little or no expansion, allowing very low forces to be applied to the pellicle and patterning device (MA).

In one embodiment, frame 234 may comprise silicon, and it may be desirable to provide a pre-stress within pellicle 231 in the range of 100 to 250 MPa, for example approximately 200 MPa. To achieve a pre-stress of approximately 200 MPa, frame 234 may be bonded to pellicle 231 at a temperature less than approximately 160 °C. For example, bonding techniques such as optical tactile bonding and hydrogen bonding can be used, which operate at temperatures of about 20 to 25 °C. Other exemplary bonding techniques that may be used with the silicon frame to achieve a pre-tension of about 200 MPa include gold diffusion bonding (operating at a temperature of about 50 °C) and anodic bonding (operating at a temperature of about 160 °C). do.

It will be appreciated that different bonding temperatures may be selected if a different amount of pre-stress is desired within the pellicle 231 . 24 is a graph showing how the pre-stress in the MoSi pellicle increases with the temperature at which the silicon frame is bonded to the pellicle. It will be appreciated that the desired pre-stress may depend on a number of factors including, for example, the composition of the pellicle 231 . As an example, in an embodiment using a graphite-based pellicle 231, a pre-stress in the range of 300 MPa to 450 MPa, for example approximately 400 MPa, may be required, and the material and bonding of the pellicle frame 234 The temperature of can be selected accordingly. In particular, the pre-stress σ in the pellicle 231 at a given temperature T can be given by:

σ = -E _pellicle ((CTE _pellicle -CTE _frame )/(1-ν _pellicle ))(TT _bonding ) (1)

Here, E _pellicle is the Young's modulus of the pellicle, CTE _pellicle is the CTE of the pellicle, CTE _frame is the CTE of the pellicle frame, ν _pellicle is the Poisson's ratio of the pellicle, and T _bonding is the junction temperature.

The method described with reference to FIG. 23 may additionally be advantageous in that the frame may be configured in any desired size and shape. In other methods of constructing a pellicle assembly, a pellicle frame formed from an etched substrate on which a pellicle is grown may be assembled onto another frame for placement on a patterning device. The method described with reference to FIG. 23 advantageously avoids additional construction (eg gluing, assembly) and reduces the number of interfaces between components, thereby reducing the generation of particles that can cause contamination. and reduce the stress applied to the pellicle 231 during manufacture. That is, the pellicle frame can be formed from a single piece rather than adding a residual substrate border and another frame element. Additionally, construction of the frame 234 may be simpler than for other pellicle assembly construction techniques. For example, the pellicle frame 234 can be machined and can be machined from a single piece of frame material.

In one embodiment, pellicle frame 234 may be coated with a chemically inert coating prior to bonding to pellicle 231 . In this way, outgassing of the pellicle frame 234 may be reduced or eliminated.

In one embodiment, the entire pellicle frame 234 may be coated with an etch resistant chemical coating used to etch the substrate 232 . The entire pellicle assembly 230 can then be constructed and cleaned prior to etching the substrate 232, thereby increasing yield.

In the previous examples described with reference to FIGS. 23 and 24 , it is explained that the frame 234 may include silicon. However, in other embodiments, the frame may include a material other than silicone. For example, frame 234 may include at least one of aluminum, titanium, beryllium, aluminum nitride, zerodur®, silicon oxide, and silicon carbide. The choice of frame material can be chosen according to the bonding temperature and the desired pellicle pre-stress.

In one embodiment, the pre-stressing of the pellicle may be selected such that the pellicle is wrinkled in a particular way (eg, to have wrinkles of a particular desired dimension) to improve the performance of the lithographic apparatus. Referring to FIG. 25 , a patterning device MA protected by a pellicle 302 is shown. A radiation beam 304 passes through the pellicle 302 and is incident on the patterning device MA. Patterned radiation beam 306 is reflected from patterning device MA, passes through pellicle 302 , and is incident on a desired area of substrate 308 . However, pellicle 302 is not completely transparent to radiation beam 304 . A portion of the radiation beam 304 is absorbed by the pellicle 302 while a portion 310 is reflected from the pellicle 302 . The reflected portion 310 may be on the order of 0.4% of the radiation beam 304, for example. The reflected portion 310 does not follow the same path as the patterned beam of radiation 306 and therefore does not impinge on the desired area of the substrate 308 . Also, since the reflected portion 310 does not interact with the patterning device MA at all, the reflected portion 310 is not patterned into the desired pattern. As such, the reflected beam 306 may cause overlay errors and/or reduced contrast.

In one embodiment, the pellicle properties are selected to cause the occurrence of wrinkles that reflect at least a portion of the incident radiation beam along a propagation path that does not intersect the substrate. Figure 26 shows an arrangement similar to that shown in Figure 25, where like elements are provided with like reference numbers. However, in FIG. 26 , the pellicle 402 is configured to be corrugated in such a way that the reflected portion 310 follows a path that does not intersect the substrate 308 . As such, in the embodiment of Figure 26, portion 310 does not induce reduced contrast or overlay errors. While it may not be possible to prevent all reflections from the pellicle 402 onto the substrate (e.g., portions that reflect from the peaks of the troughs of the corrugations), by selecting the appropriate corrugations, the reflection from the pellicle onto the substrate The amount of radiation emitted can be reduced.

The quality of the corrugation of pellicle 402 can be controlled using any of the techniques described herein for controlling the pre-stress present in pellicle 402 . Additionally, the temperature of the pellicle 402 may also be controlled. In one embodiment, the pre-stress and temperature of the pellicle 402 is selected to cause wrinkles with an angle α greater than approximately 35 mrad with respect to the plane defined by the surface of the pellicle at room temperature. However, it will be appreciated that the angle of the desired corrugation may vary depending on the optical path length between the patterning device and the substrate.

In one embodiment, the pellicle 402 is pre-stressed to approximately 240 MPa. In one embodiment, the pellicle 402 may be heated to an operating temperature of approximately 200 to 450 degrees Celsius (eg, during a patterning operation). In an exemplary embodiment in which pellicle 402 includes a pre-stress of approximately 240 MPa and is heated to approximately 450 °C, pellicle 402 has a maximum local angle α of up to about 40 mrad and a wrinkle height of the order of 10 μm. (Wh) can represent wrinkles. However, it will be appreciated that in general the corrugation height may be different and the corrugation height may depend on the material composition of the pellicle. In embodiments where the wavelength of the radiation beam 304 is on the order of 13.5 nm, the pellicle may be configured to exhibit wrinkles with a minimum height on the order of 10 μm. It was generally expected that wrinkles in pellicle 402 could increase absorption of incident radiation beam 304, but any increase in absorption of radiation beam 304 due to wrinkles having local angles less than approximately 300 mrad. was determined to be acceptable.

Pellicles may have a finite amount of time that they are valid and/or the probability of failure is within a desired threshold. For example, it may be the case that for some pellicles, after a certain period of time, the pellicle is sufficiently likely to fail that it is desirable to avoid its use. In case of a catastrophic failure of the pellicle, the elastic energy stored within the pellicle may induce breakage of the pellicle, which in turn may cause pieces of the pellicle to be ejected into other areas of the lithographic apparatus, leading to downtime of the lithographic apparatus. .

To allow a decision as to whether a pellicle should be used, one embodiment provides a wirelessly readable and writable tracking device within the pellicle frame of the pellicle. For example, a pellicle frame may include a near field communication (NFC) chip (such as an RFID "tag"). For example, a tracking device may be installed in a pellicle frame during manufacturing or mounting on a patterning device. The tracking device was provided with a serial number that uniquely identifies the pellicle and/or pellicle assembly. The tracking device may further store operational data that may be used to track the operational history of the pellicle. For example, operational data may include the number of exposures the pellicle has been exposed to, manufacturing time, total radiation dose (eg, based on the number of exposures and the known power of each exposure), and/or the pellicle reaching the end of its useful life. It may contain any other information that can be used to determine whether Additionally, the tracking device may store pellicle specific information, eg a list of offline measured parameter values (eg EUV transmission, reflection, etc.).

When a pellicle/patterning device combination is loaded into a lithographic apparatus, a transceiver component provided within the lithographic apparatus (e.g., comprising a single transceiver or separate receiver and transmitter) may (eg, by a controller) determine the pellicle's serial number and Operational data can be read. The controller can determine if one or more particular of the operational data items exceeds a threshold. For example, the controller can determine whether the number of exposures the pellicle has been exposed to or the time since fabrication exceeds a threshold. If the controller determines that one or more of the operational data items exceeds the threshold, the lithographic apparatus may unload the pellicle/patterning device combination. Additionally, the controller may cause the transceiver to write data to the tracking chip to indicate that the pellicle is unusable or has been denied for use by a particular lithography device.

If it is determined that a particular operational data item does not exceed its associated thresholds, the controller tracks the usage of the pellicle during operation. For example, the controller can record the number of exposures the pellicle is exposed to and cause the transceiver to write that data to the tracking device. Tracking data may be written to the tracking device during use or during an unloading operation in which the pellicle/patterning device is removed from the lithographic apparatus.

When removed from the lithographic apparatus, the tracking device in the pellicle/patterning device combination can be read to determine if the pellicle has been marked unusable or if one or more of the operational data items exceeds a threshold. Then, it can be determined whether to replace the pellicle for the patterning device.

27A-27C schematically depict other configurations in which a pellicle assembly may be strengthened to prevent breakage during use or manufacture. Referring to FIG. 27A , a pellicle assembly 500 includes a pellicle frame 502 supporting a pellicle 504 . Pellicle frame 502 may be fabricated, for example, as described above. A tensile layer 506 is applied to the “front” or “top” side of the pellicle component 500 (ie, such that the pellicle 504 is disposed between the tensile layer 506 and the pellicle frame 502). The tensile layer 506 may be provided on the pellicle 504 in any suitable manner (eg, by any form of deposition, or by growing the tensile layer 506 on the pellicle 504). will understand

When viewed in cross section as shown in FIG. 27A , the tensile layer 506 extends laterally inwardly (eg, overlaps or bridges) beyond the inner edge 508 of the pellicle frame 502 . The location of the inner edge 508 of the pellicle frame is typically a weak point in the pellicle assembly and is a location where pellicle assemblies often experience mechanical failure. The presence of the tensile layer 506 extending over the weak point at the edge 508 serves to maintain tension in the pellicle 504 and strengthen the pellicle assembly 500 . In this way, tensile layer 506 allows pellicle 504 to be subjected to additional pre-tension than would be possible without the presence of tensile layer 506 . As discussed in detail above, applying an appropriate and sufficient level of pretension to the pellicle 504 improves the optical properties of the pellicle assembly by preventing wrinkling. Tensile layer 508 preferably extends only inwardly over the non-optically active portion of pellicle 504 . That is, the tensile layer 508 preferably does not extend inwardly to the extent of overlapping the beam path of the radiation beam B. As in the configuration shown in FIG. 27A , it is preferred (but not required) that the tensile layer 508 has an outer extent from edge 508 that is greater than an inner extent from edge 508 to provide greater strength. ). In this way, as shown in FIG. 27A, the tensile layer 506 has a first portion 506a extending inwardly from the edge 508 and a larger second portion 506b extending outwardly from the edge 508. ).

As shown with reference to pellicle assembly 510 of FIG. 27B , tensile layer 512 may instead be applied to the “bottom” or “underside” of pellicle 504 . Like tensile layer 506 of pellicle assembly 500, tensile layer 512 of pellicle assembly 510 extends across the inner boundary between pellicle frame 502 and pellicle 504 to form pellicle assembly 510. strengthen In the configuration of FIG. 27B , a first portion 512a of tensile layer 506 extends inwardly from edge 508 and a larger second portion 512b extends outwardly from edge 508 . Additionally, in configuration 510 , second portion 512b extends over a plurality of faces of pellicle frame 502 . In particular, in the example of FIG. 27B , second portion 512b extends over all exposed faces of pellicle frame 502 (eg, all faces other than the “top” face to which pellicle 504 is applied). In this way, the tensile layer 512 may particularly strengthen the pellicle assembly 510 and allow greater pre-tensioning of the pellicle 504 .

Further, as shown in FIG. 27C , pellicle assembly 514 may include both tensile layer 506 and tensile layer 512 . The tensile layer may include any suitable material. For example, the tensile layer may include molybdenum (Mo), ruthenium (Ru), well-adhered metal layers such as aluminum (Al), titanium (Ti), tantalum (Ta), vanadium (V), chromium (Cr), It may include niobium (Nb), hafnium (Hf), tungsten (W), oxides such as TiO2 and Ta2O5, nitrides such as TiN, TaN, CrN, and SiN, or carbides such as TiC, TaC, and SiC. In general, any material that is sufficiently adherent and capable of being deposited with sufficient tensile stress (as determined by the specific requirements of the particular application) may be used. Also, the tensile layers may include a multi-layer structure in which each layer includes a different material. For example, the tensile layer may include a capping protection layer over the tension providing layer. By way of example only, the tensile layer may include a first layer of molybdenum to provide tension and a second layer of ZrO2 to act as a protective layer. Additionally, tensile layers provided on the front surface (such as tensile layer 506) may have a different structure and composition than tensile layers provided on the rear surface (such as tensile layer 512). This advantageously allows different materials to be used to match different operating conditions “above” and “below” the pellicle 504 . It will also be appreciated that the thickness of the tensile layers and the distances they extend to either side of the edge 508 may be selected depending on the particular materials being used.

In general, the configurations described above provide pellicle assemblies in which stress (eg, pre-stress) under non-operating conditions can be selected according to application requirements. For example, if it is desired to provide a lower pre-tension than is currently achievable, the lifetime of the pellicle can be improved while allowing for the desired thermo-chemical properties. That is, the foregoing technologies allow separation of the pre-stress present in the pellicle after fabrication of the pellicle assembly and the thermo-chemical properties of the pellicle. Also, in case of catastrophic failure of the pellicle, the reduced tension that can be achieved through the previously disclosed configurations allows for less elastic energy to be present in the pellicle. As such, it is less likely that fragments of the pellicle will be ejected to other areas of the lithographic apparatus due to breakage of the pellicle, thereby reducing downtime of the lithographic apparatus. Also, while the configurations described above are described with respect to pellicles used to protect a patterning device MA, it is understood that the foregoing pellicle assemblies described herein may be used for lithography and more broadly in other applications. shall. For example, the configurations described above can be used to provide pellicle assemblies for use in dynamic gas locks.

In one embodiment, the present invention may form part of a mask inspection apparatus. A mask inspection device may illuminate the mask using EUV radiation and monitor the radiation reflected from the mask using an imaging sensor. Images received by the imaging sensor are used to determine whether or not there are defects in the mask. The mask inspection apparatus may include optics (eg mirrors) configured to receive EUV radiation from an EUV radiation source and shape it into a radiation beam to be directed at the mask. The mask inspection apparatus may further include optics (eg mirrors) configured to collect EUV radiation reflected from the mask and form an image of the mask on an imaging sensor. The mask inspection apparatus may include a processor configured to analyze an image of the mask at an imaging sensor and determine from the analysis whether any defects are present on the mask. Further, the processor may be configured to determine whether mask defects detected when the mask is used by the lithographic apparatus cause unacceptable defects in images projected onto the substrate.

In one embodiment, the present invention may form part of a metrology device. A metrology device may be used to measure the alignment of a projected pattern formed in a resist on a substrate to a pattern already present on the substrate. This relative alignment measure may be referred to as an overlay. A metrology device may be placed, for example, immediately adjacent to a lithographic device and used to measure overlay before the substrate (and resist) is processed.

Although specific embodiments of the present invention are mentioned herein in the context of a lithographic apparatus, embodiments of the present invention may be used in other apparatus. Embodiments of the present invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes an object such as a wafer (or other substrate) or mask (or other patterning device). This apparatus may be generally referred to as a lithography tool. Such a lithography tool may use vacuum conditions or ambient (non-vacuum) conditions.

The term "EUV radiation" may be considered to encompass electromagnetic radiation having a wavelength within the range of 4 to 20 nm, for example in the range of 13 to 14 nm. EUV radiation may have a wavelength less than 10 nm, for example within the range of 4 to 10 nm, such as 6.7 nm or 6.8 nm.

Although the source SO is described above as being able to be a laser produced plasma (LPP), any suitable source may be used to generate EUV radiation. For example, an EUV emission plasma may be created by using an electrical discharge to convert a fuel (eg, tin) into a plasma state. A radiation source of this type may be referred to as a discharge produced plasma (DPP) source. The electrical discharge may be produced by a power supply that may form part of the radiation source or may be a separate entity connected to the radiation source SO through an electrical connection.

Although reference is made herein to a specific use of a lithographic apparatus in IC fabrication, it should be understood that a lithographic apparatus described herein may have other applications. Other possible applications include integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like.

Although specific embodiments of the invention have been described above, it will be understood that the invention may be practiced otherwise than as described. The foregoing description is intended to be illustrative and not limiting. Accordingly, those skilled in the art will understand that modifications may be made to the invention described without departing from the scope of the items described below.

1. In the pellicle assembly,

The pellicle assembly includes a pellicle frame defining a surface to which the pellicle is attached,

The pellicle assembly includes one or more three-dimensional expandable structures that allow the pellicle to expand under stress.

2. The pellicle assembly according to item 1, wherein at least one of the three-dimensional inflatable structures is formed in the pellicle frame and imparted to the pellicle.

3. The pellicle assembly according to points 1 or 2, wherein at least one of the three-dimensional inflatable structures forms a spring.

4. The pellicle assembly according to item 3, wherein the spring includes at least one V-shaped formation formed in the pellicle frame.

5. The pellicle assembly according to any of points 1 to 4, wherein at least one structure is formed within the pellicle frame and includes a plurality of springs positioned around the center of the pellicle.

6. A pellicle assembly according to clause 2 or any one subordinate thereto, wherein at least one spring is a leaf-spring.

7. The pellicle assembly according to any one of items 1 to 6, wherein at least one of the three-dimensional inflatable structures is present in the center of the pellicle.

8. The pellicle assembly according to item 7, wherein the frame includes a substrate, the pellicle assembly includes at least one spring layer between the substrate and the pellicle, and at least one spring is formed in the spring layer.

9. The pellicle assembly according to any of points 1 to 8, wherein at least one three-dimensional intumescent structure comprises a herringbone pattern.

10. The pellicle assembly of item 9, wherein the at least one three-dimensional expandable structure comprises a herringbone pattern extending over most of the entire surface of the pellicle.

11. A pellicle assembly according to any of points 1 to 10, wherein at least one three-dimensional intumescent structure induces a roughness across the surface of the pellicle.

12. In the pellicle assembly,

The pellicle assembly includes a pellicle frame defining a surface to which the pellicle is attached,

The pellicle assembly of claim 1, wherein the surface includes at least one adhesive boundary for reducing adhesive spreading.

13. The pellicle assembly of point 12, wherein the at least one adhesive boundary comprises a circular boundary.

14. The pellicle assembly according to points 12 or 13, wherein the at least one adhesive boundary comprises a line boundary.

15. The pellicle assembly according to item 14, wherein the line boundary is positioned adjacent to an edge of the frame, and the edge of the frame is adjacent to a central portion of the pellicle.

16. The pellicle assembly according to clause 145, according to clauses 14 or 13, wherein the line boundary is located between the circular boundary and the center of the pellicle.

17. The pellicle assembly of any of points 12-16, wherein at least one boundary comprises a groove in the frame.

18. The pellicle assembly of any of points 12-17, wherein the pellicle assembly comprises an adhesive substantially concentric with the circular boundary.

19. In the pellicle assembly,

pellicle frame;

pellicle; and

one or more actuators for moving the pellicle assembly toward and away from the patterning device

A pellicle assembly comprising a.

20. The actuator of clause 19, wherein the actuator operates between a closed configuration in which a substantially sealed volume is formed between the pellicle and the patterning device, and an open configuration in which the volume between the pellicle and the patterning device is in fluid communication with the surrounding environment. A pellicle assembly configured to displace the assembly.

21. In the pellicle assembly,

A pellicle frame defining a surface to which the pellicle is attached;

The pellicle frame includes a first material having a first coefficient of thermal expansion and a second material having a second coefficient of thermal expansion.

22. The pellicle assembly of item 21, wherein the first material comprises silicon.

23. The pellicle assembly of points 21 or 22, wherein the first material comprises a plurality of perforations and the second material is positioned within the plurality of perforations.

24. The pellicle assembly of any of points 21-23, wherein the second material at least partially surrounds the first material.

25. The pellicle assembly according to any one of points 21 to 24, wherein the second material comprises a metal.

26. In the pellicle assembly,

A pellicle frame defining a surface to which the pellicle is attached;

The pellicle frame is a pellicle assembly bonded to the pellicle.

27. The pellicle frame according to item 26, wherein the pellicle is an annealed pellicle, and the pellicle frame is bonded to the pellicle after annealing.

28. The pellicle assembly according to 26 or 27, wherein the pellicle frame comprises a material having a lower coefficient of thermal expansion (CTE) than silicon.

29. The pellicle assembly according to any one of points 26 to 28, wherein the pellicle frame comprises a glass-ceramic material.

30. The pellicle assembly of any of points 26-29, wherein the pellicle frame is bonded to the pellicle using a bonding procedure that operates at a temperature less than about 160°C.

31. The pellicle assembly according to any one of items 26 to 30, wherein the pellicle frame is bonded to the pellicle using at least one of optical contact bonding, hydrogen bonding, gold diffusion bonding, or anodic bonding.

32. The pellicle assembly according to any one of points 26 to 31, wherein the pellicle frame is formed in a single piece.

33. The pellicle assembly according to any of points 26-32, wherein the pellicle frame includes an inert coating to reduce outgassing.

34. The pellicle assembly according to any one of items 26 to 33, wherein the pellicle frame does not contain silicon.

35. The pellicle assembly according to any one of points 26 to 34, wherein the pellicle frame comprises at least one of aluminum, titanium, beryllium, aluminum nitride, zerodur®, silicon oxide and silicon carbide.

36. In the pellicle assembly,

The pellicle assembly includes a pellicle frame defining a surface to which the pellicle is attached,

When illuminated with a beam of radiation to pattern a substrate to be patterned, the pellicle comprises one or more wrinkles and partially reflects the beam of radiation;

wherein the one or more wrinkles are configured to reflect a portion of the radiation beam away from the substrate to be patterned.

37. The pellicle assembly of clause 36, wherein the pellicle is configured such that the wrinkles create a maximum angle greater than 35 mrad with respect to the plane defined by the surface of the patterning device.

38. The pellicle assembly according to points 36 or 37, wherein the pellicle is configured such that the wrinkles create a maximum angle with respect to a plane defined by the surface of the patterning device that is less than 300 mrad.

39. The pellicle assembly of any of clauses 36-38, wherein the pellicle is configured to reflect approximately 0.4% of an incident radiation beam during use.

40. The pellicle assembly according to any of clauses 1 to 39, wherein the pellicle comprises molybdenum disilicide (MoSi ₂ ) and the average stress in the pellicle is in the range of 100 MPa to 250 MPa at room temperature.

41. The pellicle assembly according to any one of points 1 to 40, wherein the pellicle comprises a graphite-based material, and the average stress within the pellicle is in the range of 300 MPa to 450 MPa at room temperature.

42. A lithographic apparatus arranged to project a pattern from a patterning device onto a substrate, comprising:

A lithographic apparatus comprising a pellicle assembly according to any one of claims 1 to 41 positioned in the vicinity of the patterning device to prevent particles from contacting the patterning device.

43. In the method of manufacturing a pellicle assembly,

depositing a pellicle on a substrate;

bonding a pellicle frame to the pellicle so that the pellicle is between the pellicle frame and the substrate;

Etching the substrate to leave the pellicle and the pellicle frame.

How to include.

44. The method of 43, wherein the pellicle frame is bonded to the pellicle at a temperature less than 160°C.

45. The method of points 43 or 44, further comprising annealing the pellicle after depositing the pellicle on a substrate and prior to bonding the pellicle frame to the pellicle.

46. In the pellicle assembly,

A pellicle frame defining a surface to which the pellicle is attached;

A pellicle assembly wherein a computer readable and writable tracking device is provided on or in the pellicle frame.

47. The pellicle assembly of 46, wherein the computer readable and writable tracking device is configured to store an identifier of the pellicle and/or the pellicle assembly.

48. The pellicle assembly according to points 46 or 47, wherein the computerized tracking device is configured to store pellicle specific attributes and/or operational data indicative of a history of use of the pellicle.

49. A lithographic apparatus arranged to project a pattern from a patterning device onto a substrate, comprising:

A lithographic apparatus comprising a controller comprising a processor configured to execute computer readable instructions which cause a transceiver component to read from and write to a tracking device of a pellicle assembly according to any one of claims 46 to 48.

50. The lithographic apparatus of 49, wherein the computer readable instructions are configured to cause the processor to obtain one or more operational data items from the tracking device and determine whether the one or more operational data items exceed a threshold.

51. The computer readable instructions are configured to cause the processor to cause the lithographic apparatus to unload the pellicle assembly in response to a determination that the at least one operational data item exceeds a threshold. .

52. The lithographic apparatus of 51, wherein the computer readable instructions are configured to cause the processor to cause the transceiver component to write data to the tracking device indicating that the pellicle assembly has been unloaded.

53. The computer readable instructions of clauses 50 or 52 further cause the processor, in response to determining that the at least one operational data item does not exceed a threshold, to cause the transceiver to track the tracking device during use of the lithographic apparatus. A lithographic apparatus configured to write operational data to a lithographic apparatus.

54. In the pellicle assembly,

a pellicle frame defining a surface to which the pellicle is attached; and

at least one tensile layer in mechanical communication with the pellicle and extending inwardly beyond the inner edge of the pellicle frame;

A pellicle assembly comprising a.

55. The pellicle assembly of clause 54, wherein at least one of the one or more tensile layers is provided on a top surface of the pellicle such that the pellicle is positioned between the tensile layer and the frame.

56. The pellicle assembly according to points 54 or 55, wherein at least one of the one or more tensile layers is provided on a lower surface of the pellicle.

57. The pellicle assembly of any of clauses 54-56, wherein the one or more tensile layers comprises a first tensile layer provided on the top surface of the pellicle and a second tensile layer provided on the bottom surface of the pellicle.

58. The method of any of clauses 54-57, wherein at least one of the one or more tensile layers comprises a first portion extending inwardly from the inner edge of the pellicle frame and a first portion extending outwardly from the inner edge of the pellicle frame. A pellicle assembly comprising two parts, wherein the second part is longer than the first part.

59. The pellicle assembly of any of clauses 54-57, wherein at least one of the one or more tensile layers comprises a multilayer structure.

60. A lithographic apparatus arranged to project a pattern from a patterning device onto a substrate, comprising:

A lithographic apparatus comprising a pellicle assembly according to any one of claims 54 to 59 positioned in the vicinity of the patterning device to prevent particles from contacting the patterning device.

61. A dynamic gas lock for a lithographic apparatus comprising a pellicle assembly according to any of clauses 1 to 41, 46 to 48, or 54 to 59.

Claims (20)

In the pellicle assembly,
A pellicle frame defining a surface to which a pellicle is attached and supporting the pellicle around an outer periphery of the pellicle,
The pellicle frame is bonded to the pellicle,
The pellicle is a pellicle assembly comprising molybdenum disilicide (MoSi ₂ ). According to claim 1,
The pellicle assembly having a thickness selected from 15 to 50 nm. According to claim 1,
The pellicle is an annealed pellicle assembly. According to claim 1,
The average stress in the pellicle is selected from 100 MPa to 250 MPa at room temperature. According to claim 1,
The pellicle frame includes an attachment mechanism configured to removably attach the pellicle frame to a patterning device. According to claim 1,
wherein the pellicle frame includes a mechanism configured to translate the pellicle frame in a direction toward and away from the patterning device to close and open a region between the pellicle and the patterning device. According to claim 1,
The pellicle frame is a pellicle assembly comprising a material having a lower coefficient of thermal expansion (CTE) than the coefficient of thermal expansion (CTE) of silicon. According to claim 1,
The pellicle frame is a glass-pellicle assembly comprising a ceramic material. According to claim 1,
The pellicle frame includes a first material having a first coefficient of thermal expansion and a second material having a second coefficient of thermal expansion. According to claim 1,
The pellicle frame is a pellicle assembly formed of a single piece. According to claim 1,
The pellicle frame comprises an inert coating to reduce outgassing. According to claim 1,
The pellicle frame is a pellicle assembly that does not contain silicon. According to claim 1,
wherein the pellicle frame comprises at least one selected from aluminum, titanium, beryllium, aluminum nitride, zerodur® ceramics, silicon oxide or silicon carbide. According to claim 1,
The pellicle assembly according to claim 1, wherein the pellicle frame is bonded to the pellicle using a bonding procedure operating at a temperature of less than 160 °C. According to claim 1,
The pellicle frame is a pellicle assembly bonded to the pellicle after annealing. According to claim 1,
The pellicle frame is bonded to the pellicle using at least one selected from optical contact bonding, hydrogen bonding, gold diffusion bonding, or anodic bonding. A dynamic gas lock for a lithographic apparatus comprising a pellicle assembly according to claim 1 . A lithographic apparatus arranged to project a pattern from a patterning device onto a substrate, comprising:
A lithographic apparatus comprising a pellicle assembly according to claim 1 positioned in the vicinity of the patterning device to prevent particles from contacting the patterning device. In the method of manufacturing a pellicle assembly,
depositing a molybdenum disilicide (MoSi2) pellicle on a substrate; and
Annealing the pellicle after depositing the pellicle on a substrate
How to include. According to claim 19,
The substrate forms a pellicle frame, and the pellicle frame is bonded to the pellicle at a temperature of less than 160 ° C.

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